light flashing signaling system Another point of contact with for ships, and shoes for walking computing is through his Dec. 26th on water. discovery of a new class of numbers, both infinitely large He had a reputation for being and infinitesimally small, called somewhat eccentric: he once “surreal numbers”, which Charles Babbage counted all the broken panes of popped up while Conway was Born: Dec. 26, 1791; glass in a factory, and published studying Go. They were first a paper about it, noting that 14 London; Probably at 44 Crosby named in Donald Knuth's [Jan of the 464 breakages were Row, Walworth Road 10] 1974 book "Surreal caused by “drunken men, Died: Oct. 18, 1871 Numbers: How Two Ex-Students women, or boys”. He once baked Turned on to Pure Mathematics himself in an oven at 265°F Babbage's Analytical Engine and Found Total Happiness". [Dec 23] originated the idea of a (130°C) for four minutes programmable computer, “without any great discomfort” When Conway first booted up inspired by his earlier designs to “see what would happen.” He his computer, it generated ten for a Difference Engine [June 14] calculated the chances of a man random dates (e.g. 5/3/2020, for calculating polynomial rising from the dead, and 29/4/1803) as a password test. functions. Neither machine was directed a ballet featuring He had to enter the day of the built in his lifetime, but see [four colored lights. Perhaps most week for each one before the entries forward]. Fortunately, he famously, he suffered a long- computer let him in. Using his gave fairly detailed descriptions running feud with London’s own Doomsday rule to do the of them in his 1864 organ grinders [July 25]. mental calculation, he could autobiography, “Passages from usually come up with the correct There is a Babbage Crater on the the Life of a Philosopher", and day within a few seconds. moon, a Babbage River in the his son, Henry, supplied more Yukon, and Babbage Mountains His father was a technician in technical information in in Australia. Half of Babbage’s the chemistry lab at the “Babbage’s Calculating Engines” brain is preserved at the Liverpool Institute for Boys, a in 1889. The book collected all of Hunterian Museum in the Royal school attended by Paul his father’s writings on the College of Surgeons in London. McCartney and George Harrison machines, together with The other half is on display of "The Beatles" [June 25; Oct 1; previously unpublished plans across town in the Science Oct 8]. and notebooks. Museum. Do the two pieces fit The Guardian newspaper together, like a jigsaw? described Conway as “Archimedes, Mick Jagger [Dec 7], Salvador Dali, and Richard John Horton Feynman [May 2], all rolled into one.” Conway Born: Dec. 26, 1937; Liverpool, UK Joseph Sifakis Died: April 11, 2020 Born: Dec. 26, 1946; Although Conway worked in Heraklion, Crete many areas related to number theory and recreational math, Sifakis is one of the pioneers of he's perhaps best known to model checking which aims to computer scientists for his verify that a mathematical "Game of Life" cellular model of a system matches its automaton, which was specification. Model checking is popularized in an article by essential in hardware design to Martin Gardner [Oct 21] in the validate safety requirements for Babbage's brain at the London Oct. 1970 issue of Scientific concurrent systems. Science Museum. Photo by Marcin American. Since then, "Life" has Sifakis' lab developed the SCADE Wichary. CC BY 2.0. spawned hundreds of programs, tool for checking real-time web sites, and articles. systems, which has since Babbage dabbled in many areas Gardner actually wrote quite become a de facto standard in of Victorian engineering: he frequently about the aeronautics. He also played a designed cow-catchers for recreational aspects of Conway’s major role in the development of railway engines, an automaton work. For instance, he discussed the BIP (Behavior, Interaction, for playing tic-tac-toe [Aug 25], Conway’s game of Sprouts (July Priority) component framework and a mail system for delivering 1967), Hackenbush (Jan. 1972), for system design. canisters along wires strung and his angel and devil problem Sifakis is a commander of the between towers. He invented a (Feb. 1974). Greek Order of the Phoenix. The

1 phoenix symbolizes the rebirth deliberately put errors into the of the Hellenic nation; it is not a drawings to mislead anybody secret society founded by Albus that might try to sell them.” Dumbledore. Modern manufacturing methods were employed to build the engine but only to a level of Expando-Vision precision possible in Babbage's time. The fact that the machine Dec. 26, 1983 worked showed that Babbage’s failure to build it wasn’t due to John C. Dvorak, writing in the limitations of nineteenth- InfoWorld magazine, described century engineering. It had his encounter with Expando- much more to do with disputes Vision at COMDEX [Dec 3]. The with his engineer, Joseph gadget was attached to a TV set Clement, his frequent design and flashed subliminal messages tinkering, and poor project on the screen while you watched management. regular TV programmes. In 2000, Nathan Myhrvold [Aug The makers, Stimutech of East 3] funded the construction of the Lansing, Michigan, emphasized engine's output unit, which can its self-help uses (e.g. for weight- both print and create plates for loss and for quitting smoking), use in printing presses. but also sold a “Sexual Invitation” module that flashed Myhrvold also commissioned a up messages of 'irresistible' second Difference Engine, which seduction, such as: "Let's make took 3.5 years to finish, love" and "Let's get naked". including four months to get it to run reliably. It was built by a Expando-Vision could run on the team led by Richard Horton who VIC-20 [May 00], Commodore 64 had taken over from Crick (who [Jan 7], or Atari 400/800 [Nov was then 80 years old). 00], but there was no Apple II version [June 5]. For more Dvorak, see [Sept 27], [April 1].

Difference Engine No. 2, Twice Dec. 26, 1991 London’s Science Museum put a working 2.6-ton, 4000-part Difference Engine No. 2 [June 14] on display to commemorate The Difference Engine at the 200th anniversary of Charles Intellectual Ventures. Photo by Babbage’s birth [four entries Alan Boyle. (c) earlier]. The project was begun https://www.geekwire.com in 1989 by Doron Swade, then curator of computing at the This second engine is on display museum. Also on display was in the foyer of the Intellectual part of Babbage's unfinished Ventures (IV) lab at 14360 SE Analytical Mill, and half of the Eastgate Way, Bellevue in great man’s brain. Washington state. Wired The engine's engineering team, magazine claimed that the led by Reginald Crick, worked engine was, at some point, from Babbage’s original plans located in Myhrvold’s living and twenty large design room. drawings. Crick said “There were some mistakes, but we think he was afraid of industrial espionage. We think Babbage

2